Method and apparatus for deep beading thin gauge metal



June 14, 1960 F. N. LA MARTINEZ I 2, 2

METHOD AND APPARATUS FOR DEEP BEADING THIN GAUGE METAL Filed Jan. 3,1955 4 Sheets -Sheet 1 FIG 3 mm) i J n 1 1950 F. N. LA MARTINE 2,940,502

METHOD AND APPARATUS FOR DEEP BEADING THIN GAUGE METAL Filed Jan. 3,1955 4 Sheets-Sheet 2 INVENTOR.

Francis N. LuMuriine BY a yam June 14, 1960 F. N. LA MARTINE 2,940,502

METHOD AND APPARATUS FOR DEEP BEADING THIN GAUGE METAL Filed Jan. 3,1955 I 4 Sheets-Sheet 3 Francis N. LuMorfine BY WKM June 14, 1960- F. N.LA MARTINE 2, 2

METHOD AND APPARATUS FOR DEEP BEADING THIN GAUGE METAL Filed Jan. 3,1955 4 Sheets-Sheet 4 FIG.

FIG. 12 2O INVENTOR.

FIG- 4 Francis N. LoMurflne United States Patent IVIETHOD AND APPARATUSFOR DEEP READING THIN GAUGE METAL Francis N. La Mai-tine, Irving, Tex.,assignor to Chance Vought Aircraft, Incorporated, Dallas, Tex., acorporation of Delaware Filed Jan. 3, 1955, Ser. No. 479,405

11 Claims. (Cl. 153-73) The present invention relates to the stiffeningby beading and corrugating of closed uniform sections of thin material.It relates to. the use of an integral rolled bead. More specifically,this invention pertains to the circular, deep draw roll forming of abead stifiened section of thin gauge metal.

The disclosed invention is particularly adaptable for the stiifening ofthin metal sections of various forms. While 1 illustrate only uniformcylindrical shape sections, obviously closed sections of elliptical,kidneyshaped, or other irregular shapes are formable. My invention isparticularly suitable for use in structures where weight control is avery critical factor, as in various vehicles, including aircraft forexample. From the disclosed apparatus and new method of forming deepbeads in the thin gauge metal, thinner, lighter, and higher heatresistant metals as titanium may now be successfully used to greateradvantage, as in the shrouds for jet engine afterburners for example,Where weight saving materials are highly desirable.

I disclose further a new device and new method for stiffening a cylinderor any closed section of material without the addition of weight andwithout the cost being made prohibitive.

Briefly, the mechanism for the deep drawing of annular reinforcing beadsin thin gauge metal, shaped into cylinders for example, consists of twopairs of special, concentric hoops and a pair of cooperating male andfemale rolls closely positioned between each pair of hoops. As the headis formed or rolled in the material between the two pairs of hoops, thematerial necessary for the bead is drawn from between one pair of hoopsor the other, or from between both pairs to provide accurate control ofthe forming and positioning of the stifi'ening bead.

The principal object of this invention is to produce a means forstifiening thin gauge metal sections.

Another object of this invention is to form a simple, light weight,durable, and inexpensive to manufacture stiffened section of metal.

A still further object of this invention is to stiifen closed sectionsof thin metal, as stainless steel or titanium, by forming deep beads inthe peripheral wall surface of the sections.

Another object of this invention is to provide greater accuracy in theforming and positioning of deep beads or corrugations in the peripheralwall surfaces of thin metal sections.

Another object of this invention is to provide a successful method forforming deep beads in thin sheets of titanium metal.

Another object of this invention is to provide a separate beadedstilfener that may be applied directly to the shell to be rigidified.

Other objects and advantages of the invention will be apparent from thefollowing detailed description, together .with the accompanyingdrawings, submitted for purposes 2,940,502 Patented June 14, 1960.

ice

of illustration only and not. intended to define theLsQOpe; of theinvention, reference being had for thatpurpose to the subjoined claims.

Brief description of figures Fig. 1 is a perspective view of a sectionor cylinder of very thin metal that has been stiffened by the. forming,of deep beads therein;

Fig. 2 is a perspective view of a section or cylinder of very thin metalillustrating, by the weakness of the material and the form it assumesbefore it has been.- stiffened, how thin the metal may be and yet can besuccessfully headed by the disclosed method;

Fig. 3 is a perspective view of the pair of matching female and malerolls in position for. the forming ofinternal beads;

Pig. 4 is a perspective view of the rolls of Fig. 3. when forming aninternal head in a section of material;

Fig. 5 is a plan view of the portion of the internal hoop with the latchmechanism;

Fig. 6 is a side view, with parts in section, of the internal hoop latchmechanism locked in extended. posi-. tion;

Fig. 7 is: a side view, with parts in section, of the iiiternal hooplatch mechanism in extended position, butunlocked; V

Fig. 8 is a side view, with parts in section, of the ilkternal hooplatch mechanism. as it is moving toward col; lapsed position;

Fig. 9 is a side view, with partsin section of the in-. ternal hooplatch mechanism locked in collapsedposition',

Fig. 10 is a perspective view of both the internal and external hoops inposition for clamping-the material to be beaded;

Fig. ll is an enlarged vertical sectional view of the mechanism whereinthe solidline position illustrates. a portion of the rolls, hoops, andsection of thin material, prior to the forming of the external bead andth dotted line position showing partial penetration of the upper roll bythe lower roll;

Fig. 12 is an enlarged vertical sectional view of a POI! tion of therolls and section of thin material after the forming of a completeexternal bead;

Fig. 13 is a perspective view similar to Fig. 4, but with the rollsreversed in position to form an external bead in the section ofmaterial; and

Fig. 14 is a perspectivev view of a stiffener. used as'an alternativemeans of reinforcing a thin gauge cylindrical section.

Detailed description of apparatus for forming deep beads in thin gaugemetal Stifier and lighter closed sections of thin metal are desired andrequired in vehicles oftoday, particularly in aircraft. This inventionis very adaptable to the forming of a stifier and lighter shroud wrapperof titanium or the like metal for a jet engine or the afterburnertherefor, wherein the forming of deep beads is diflicult due toexcessive elongation with resulting reduction of thickness, excessivewrinkling, tensile failure, cracks along the axis of the bead, workhardening, or excessive springback.

Referring to the drawings, shell 20 is. a closed section of very thinmaterial to be stiffened and rigidified as illustrated in Fig. 2 in theshape or form it assumes before it has been stiffened, and the shell isshown in Fig. 1 after it has. been stiifened with deep drawn beads orgrooves 21 and 22.

The mechanism for deep drawing the grooves consists of male and femalebead forming drive rolls 30 and 151, respectively, one of the rollsbeing closely spaced between two internal work-engaging hoops or drawrings 40 and various positions it may assume. This latch mechanismcomprises a linkage system with provisions for contraction andexpansion'of the hoop, and with provisions for locking of the hoop ineither the contracted or expanded positions. Furthermore, a'fineadjustment of elongation of the hoop may be effected to insure properfitting between the hoop and the cylinder of material as will bedescribed hereinafter.

'Inte rnal split hoop 40 is formed circular from an elongated channelmember with the base of the channel forming the outer peripheral surfaceof the hoop. The

two contiguous split channel hoop ends 42 and 43 of hoop 40 are beveledas shown in Figs. 6-9 forease of collapsibility and areinterconnected'through a linkage system. Welded near one end, 42, of thehoop and within the channelis a block with a socket headed; oval pointset screw 45 threaded therethrough. The portion of the set screw withthe oval point projecting through block 44 has a reduced neck portionnear the'pointed end. A yoke 46, slideable in the split channel end 42is adapted to receive the above-mentioned portion of the set' screw.This latter portion of the set screw is freely rotatable in yoke 46 and,as illustrated in Figs. 5 and 6, I

is maintained therein with pin 47 in yoke 46 normal to the set screw andcontiguous with the reduced neck portion. Yoke 46, being 'slideable inthe channel hoop, accordingly projects from the end 42 thereof toprovide an adjustable extension of the channel end. The other end of setscrew 45 is provided with a socket for rotation of the screw and theresultant slideable movement of yoke 46 varies theeffec tive length ofthe channel end.

42; Because set screw 45 is actuatedin only one straight, axialdirectionas it screws through block 44 and as the yoke 46 slides in anarcuate path in the channel hoop, the pointed end of the set screw isoval shaped to' prevent binding between the set screw and the yoke.Accordingly, a fine adjustment of elongation of the hoop may be effectedto provide. an adequate and proper fitting of the internal split hoop,40 or 41, inside thecylinder material. Pivotally connected to slideableyoke 46 is one link 48 of the two pivotally interconnected scissorlinks, 48, 49. 'The other link 49 of said pivotally intercon nectedscissor links is pivotally connected to a pair of :hlocks indicated at50.; .The blocks 50 are welded in the manner the other end 43 of thehoop, but spaced from the tip of the end approximately the length of thetwo scissor links when collinear with each other, Fig. 6 or 7. Withtheends-of the internal hoop connected together through pivotallyconnected links, the dimension of the circumference and accordingly thediameter of the hoop may be varied by moving one end of the hoop, leftend 42 of Fig. 7 or 8, up and inside or overlying the other hoop end 43to facilitate accurate positioning of the internal hoop in the sectionor cylinder of material to be headed. The internal hoop may be unfoldedto expanded position, as shown in Fig. 7, to grip the shell 20, or thehoop may be folded to collapsed position, Figs. 8 and 9 to permit itsease of adjustment, positioning, or removal from the cylinder. g p

' The internal split hoops 40 and 41 are each provided with a lock screw51, Figs. 6-9, to maintainthe hoop-in either of the two extremepositions, the extended or expanded position and the contracted orcollapsed position. Lock screw 51 is detachably secured in link 48 withpins 52. A projecting end of the lock screw cooperates with "a threadedaperture in juxtapositioned rest pad or lock screw stop nut 53A which is"welded in the channel hoop to lock the scissor links in collinear oropen position. After the hoop is extended-to the expanded position ofFig. 7, it is then looked in'the expanded position with lock screw 51 asillustrated in Fig. 6. In the other scissor link 49 is forni'ed a stopnut or rest pad 53B with a threaded opening to accommodatelock screw 51.Accordingly, the collapsed hoop of Fig. 8 may be locked and maintainedin contractedposition ,by the co operation between lock .screw 51 andstop nut 5313, as illustrated in Fig. 9.

. Rollers 54, Figs. 5 and 6, with spacing washers 56 are journaled onstuds55 which are secured at the right end 43 of the internal channelhoop or annulus. Rollers 54 are so positionedon the edge of hoop channelend 43 that hoop end 42 abuts the rollers and rides up and on them whenthe hoop is contracted andthe hoop end 42 is moved to overlappedposition with hoop end 43, Fig. 8 or 9. Rollers 54 accordingly providean antifriction device for facilitating collapsibility of the hoop andits latch mechanism when unlocked.

- A second pair of external Work-engaging hoops 60, 61 are utilized inconjunction with the internal hoops 40, 41, respectively, in that eachof the external hoops surrounds its respective internal hoop so thateach of external hoops 60 and 61 is concentric with hoops 40 and 41,respectively, with cylinder 20 positioned between the external andinternal hoops, noting Figs. 10 and 13 particularly. .As seen in Figs.10 and 13, I utilize an adjustable swivel bolt 62 and yoke. 63, or thelike, type of adjustable clamping means connecting the ends of a steelband forming each of the external hoops 60 and 61. This adjustableclamping device is utilized to tighten the external hoops aroundthe-cylinder to be beaded to provide additional clamping action to thatof the internal hoopsof the material of shell '20 and to preventwrinkling when forming the external beads. Accordingly, in the forming.of external beads, externalhoops 60, 61 provide additional control ofhow 'of material over internal hoops 40, 41.

From the above description, the lightness inweight, high strength andsimplicity of construction, and ease'of manipulation of both internaland external draw rings or hoops are featuresofi particular consequence.

Male and female rolls 30'and '31, Fig. '3, are utilized to form thebeads 21 or 22 in a sectionofcylinder 20; a detail description of therolls, per 'se, is as follows: Y

Male roll 30, Figs. 11 and 12, has a rib 32 centered in the peripheralcylindrical surface thereof. While ribs of various shapes and depth havebeen tried, depending on the degree of'rigidity desired to be impartedto the section of material 20, I- have found substantiallysemicylindrical ribs to be preferable. Accordingly, rib 32 on the maleroll 30 is circular over'the crest thereof with the sides of thecircular crest smoothly contoured to shoulders 33 through fillets 36.The shoulders 33' of male roll 30 must, of necessity, slope downward-asviewed in Figs. 11 and 12, depending on the hardness of the material tobe headed. In the 'rolling'of titanium for example, this slope isrequired to be approximately 8 degrees below the horizon to provide forspringback, whereas only a slope of 6 degrees is required for springbackin stainless steel.

Female roll 31, of the same diameter and width as 'male roll 30, has agroove 34 centered in the peripheral cylindrical surface thereof andsloped shoulders 35 contoured to the groove through fillet 37 to providea substantially contiguous surface with the peripheral cylindricalsurface of the male roll 30. However, when the two rolls 30 and 31 arein juxtaposition with each other,

'as when rolling a head 21, Fig. 12, most of the parts of the peripheralsurfaces of the two rolls are not exactly equidistant from each other.This is to prevent flattening, thinning, marring and scratching, andweakening of the material in the bead. Only the surfaces of the fillets36- of the male roll rib32 are equidistant from; the surface of thefillets 37' of: the female roll' 31 As shown: in Figs. ll and 1-2, theslope of the female roll shoulders 35 is approximately 6 degrees belowthe horizon to provide for springback when rolling titanium, forexample.

Due t'othe above described slopes of the-shoulders. 33 and 35 of themale and female rolls, respectively, the: distance between the shouldersof the rolls, Figs. 11 and I2 gradually increases from the filletoutward to the edge of the roll. Also, the radius of curvature of thegroove 34 is greater than the radius of curvature of the crest of rib 32to provide for the distance between the surfaces of the rib 32 on themale roll 30 and the groove 34, on the female roll 31 to increase fromthe fillets 36, 37 of the two rolls inwardly to the center of the crestof the rib 32 or the center of the groove 34. Accordingly, no coiningaction and thinning of the material over the crest of the rib 32 norover the shoulders 33 of the male roll will result during the rollingoperation.

Method of forming deep beads in thin gauge metal Broadly, the externalhead 21 is rolled in the shell 20 with the two pairs of hoops or drawrings, and 60, and- 41 and 61, positioned each in contiguity with thesides 38, '39 of the rolls 3% and 31-. With the rings so placed, theamount of material flow therebetween each pair of hoops iscontrolled sothat it can be drawn from either end of the shell or both.

While various methods may be utilized in the practice of this invention,the preferred method of using the disclosed hoops and rolls and offorming a deep bead or beads in thin gauge metal comprises positioningthe two internal draw hoops, 40 and 41, in collapsed condition, Fig. 9,internally of one end of the shell 20, both hoops equally spaced on eachside of the proposed position of the bead in the shell. The internaldraw hoops 40, 41 are so spaced that internally positioned male roll 30fits snugly therebetween when rolling the bead 2.1 in the shell, wherebyboth sides 38 of the roll 31 are in contiguous relationship with theinternal hoops. The internal hoop, 40, nearest the finished end of theshell is expanded, Pig. 6, to a predetermined compression until thefriction between the hoop and the inner surface of the shell is greatenough to prevent any relative movement be tween the shell and the hoop.The other internal draw hoop, 41 is expanded against the inner surfaceof shell 20 until it is firmly held therein. Then to provide additionalcontrol of material flow and to prevent wrinkles when forming theexternal bead, expanded external hoops 6i? and 61 are circurnpositionedexternally of the cylinder ZG'directly opposite or on the other side ofthe shell material from the internal hoops .0 and 41, respectively, Fig.13. External hoop 60 is contracted to a predetermined tension until thefriction between the hoop and the outer surface of the shell is greatenough to prevent any relative movement between the shell and the hoop.The other external hoop 61 is contracted against the outer surface ofshell 20 until it is firmly maintained therearound. Then the male roll39 is inserted in the shell between the internal draw hoops 4t), 41, andthe female roll 31 is positioned externally of the shell directly0pposite to and in coplanarity with the other roll 30 and snugly fittedbetween exterior hoops 66 and 61 and in contact with the outer surfaceof the shell, as illustrated in Figs. lll3. With the hoops so positionedon the shell 26 and contiguous with the rolls, the external head 21 isrolled, Fig. 13. During the rolling operation, material is drawn fromthe cylinder 26 overall length and flows over the internal draw hoop 41and under the external hoop 61. This flow of material is controlledbyvarying the tension in the material as it flows between the internaland external hoops 41 and 61, in forming the sad. The tension in thematerial as it is rolled. is controlled by the radial force between thehoopsand the sheil' material, which force is effected by circumferential6 adjustment of the hoops. Proper control of the tension furtherprevents wrinkling and cracking of thevbead. Ex ternalhoops 60, 61likewise perform the function. ofpreventing wrinkling of the cylinder.

When the cylinder is rotated about its axis by contact between the beadforming rotating drive rolls 30 and 31 in forming an external bead 21,the innermost end faces of the draw hoops 4t), 41 are in contact withthe sides: 38 of male roll 30. As pressure on the male roll 30 isincreased outwardly, Fig. 11, towards the female roll. 31, the materialis rolled into the female roll. groove 34with the correct predeterminedtension. 7 I

The diameter of each draw hoop 40, 41 and hoops 60, 61 is adjustable(within limits) wherein the radial hoop pressure against the cylinder byboth external and internal hoops may be adjusted for controlling thefriction between the hoops and the shell or cylinder. Thus, control isprovided of the amount of material or axial flow of material drawnthrough the hoops, Fig. 13. Accordingly, in the forming of a singlestiffening bead for example, the material for the bead may be suppliedfrom one side, or the other, or both. Therefore, very accurate controlof the how of material from either side of the rolls for forming a headis maintained. This accuracy is carried through in the forming ofbellows for example. In this operation, the past methods involve spacingeach pair of head or corrugation forming rolls from the last succeeding.bead formed, as disclosed by Fulton, U.S. 947,229. Accordingly, anydeviation or inaccuracy made in one bead or in the spacing between twobeads of the bellows is carried on or additive thereto throughout the.whole operation. In the present invention, the rolls may bev positionedat an exact particular distance from the finished end. of the bellowsand the next succeeding head. or corrugation formed by feeding thematerial for the bead from the unbeaded end of the bellows. Therefore,the inaccuracies of each head made is not accumulative throughout thebellows as is true in former methods of forming a multiplicity of beadsor corrugations.

The above method of using the disclosed apparatus for deep beading hardmetal as titanium is the best and most economical method found. Theprincipal reason for the success of the disclosed method of forming hardmetals over other methods as drop hammering, stamping, etc., is deemedto lie in the fact that impact shock, which is unavoidable, inherentlycauses failures in the metals formed by the prior methods. This methodwholly alleviates impact shock material failure, as plastic flowqualities of low-ductility material are encouraged. The material forforming the beaded cylinder is placed between the forming rolls with thegrain of the material parallel to the axes of rotation of the formingvrolls, i.e., the bead longitudinal circular axis will be normal ortransverse to the grain. As the material passes between the formingrolls, greatest plastic flow results. with the grain, or in thedirection of force applied, and accordingly the grain of the cylindermaterial lies parallel to the longitudinal axis of the cylinder formed.The plastic flow of the metal is also augmented by relaxation during theforming cycle which prevents fatigue failure of the metal. This flow andrelaxation during the forming cycle is indigenous only to this process.Plastic flow of the metal is initiated by the combined action of therollers and draw rings. Tension forces on the metal 20 as it is drawnfrom the length of the cylinder being rolled produces compression andtension stresses within the metal material thickness at the points oftangency of the forming rolls 30 and 31 as the roll center-to-centerdistance decreases in the bead forming operation. In the first part ofthe rolling op.- eration, Fig. 11, the portion of the shell material 20between the surface contiguous with the female roll fillet 37 and theneutral bend line of the material is caused to be in compression and theportion of the shell material between: the neutral bend line and theother surface of the material is caused to be in tension. Likewise, theportion other surface of the material is caused to be in tension.Tension is exerted 'across'the full thickness of the shell material 20.between the above described areas. .In the latter part of the rollingoperation, Fig. 12, wvith the .of the male roll and is placed intension, while the portion of the shell material between the neutralbend line and the other surface of the material that was in tension haslikewise now moved up to overlie male rib 32 and is placedin'compression. If all material is drawn solely from one side of theroll to form the beads 21 M22, further plastic flow and reversal ofstresses is evidenced in that portion of theshell material 20 formerlyover the circular surface of the male rib 32 and which eventuallyoverlies the reversed curved fillet 36 of the male roll 30; This plasticfiow is finally arrested within the material thickuesswhen the rolls andmaterial attain 100% bearing through. their entire profile section.Coining of the material'between the fillets 36 and 37 of the'female andmale rolls, respectively, then stops plastic flow and minimizesspringback. During each revolution of rolling,

as the material is gradually formed between the rolls, all material inthe metal shell being formed that is not in contact with the rolls is ina state'of relaxation. This cycle of forming utilizing plastic flow andrelaxation withinthe metal results in maximum forrnability' and minimumfailures. 7

Internal beads 22.of unusual proportions of width to depth can also beformed in very thin gauge materials from round, elliptical, and othercurved cylindrical'or conical shells 20 by reversing the positions ofmale and female rolls 30 and 31, respectively, as disclosed in Fig.Dueto the low percentage of elongation, this process has 'proven highlysuccessful for cold forming of titanium that otherwise would Workhardenand crack.

ln theforming of the internal beads 22, the external hoops 60, 61 may beomitted. Accordingly, during the rolling operation, the material for thebead is drawn from the shelloverall length and flows over either one orboth circumferentially adjustable hoops or draw rings, 40, 41. In theforming of the internal beads 22, wherein the-internal hoops 40 and 41are .position ed contiguous with the sides 39 of the female role 31, theradial force opposing the tension of the material flow toward the centerof the bead is controlled solely by the circumferential. adjustment andrelease lock mechanism of the in ternal draw rings 40,- 41 describedabove.

7 Modification In place of heading the jet engine shroud or shell 20,per se, a separate stiffener may be formed and attached as by 'riveting,spot welding, or the like, to the shell. This stiifener is formed from athin strip of metal bent in a circle. While a single stiffener mayconsist of one ormore attached curved or arcuate strips, I prefer andillustrate, Fig. 14, one formed from two curved strips or halves, 70 and71 joined together to provide one circular or endless stiffener stn'p.With the adjacent ends of the strips maintained overlapped with eachother, a head 72 is rolled between the edges of the strips for the fulllength thereof. Accordingly, simultaneously with the rolling of the headin the full length of the stiffener strip, the overlapped edges areheaded and formed into 'material'is caus'ed tobe;'in compression and theportion of the shell material between neutral bend line and thedescribed hereinbefore areutilized', a different and more simpleinternal hoop may be utilized. This internal hoop may be a solid,unadjusta'ble ring, as its diameter controls of sets the insidediameter of the finished stiifener. With the use of the constantdiameter internal hoops, the control of material flow is provided solelyfrom the external hoops. Another feature in forming the bead in thestiffener comprises the rolling of the'bead with the grain of thematerial normal to the longitudinal circular axisof the bead. Thereforewhen the head is across the grain, beads of various shapes and depthscan be produced without the danger of cracking.

Either internal or external beads 72 may be formed in the stiffener 70,71, as in the foregoing description in the forming of the beads 21 or 22in shell 20. Accordingly, a beaded stiffener 70, 71 is provided that isequally adaptable as a reinforcing member mounted on either the insideor outside diameter of the shell 20.

While only shells, i.e., cylinders or conical sections, of metal aredescribed in the instant disclosure, obviously shells of other materialsmay be beaded.

It will be obvious to those skilled in the art thatvarious changes maybe made in the invention without departing from the, spirit and scopethereof and therefore the invention is not limited by that which isshown in the drawings and described in the specificatiombut only asindicated in the appended claims.

. I claim: r

1. A method of rolling a deep head in a cylinder of thin gauge metalwith internal and external forming rolls and a pair of circumferentiallyadjustable work-em gaging draw rings, the walls of said cylinder havinginner and outer surfacesrand each of said rolls having sides comprising,positioning said'rolls on opposite sides ofthe cylinder walls forrolling the beads therein be tween the rolls, positioning one of saidcircumferentially adjustable work-engaging draw rings in contactwith oneside of one of said rolls andin contact with one wall surface of thecylinder, positioning the other circumferentially adjustablework-engaging draw rings in contact with the other side of said one rolland in contact with said one wall surface of the cylinder, and varyingthe lengths of both of said adjustable work-engaging draw rings forcontrolling the friction between both said adjustable workengaging drawrings and said cylinder one wall surface for flow control of thecylinder material to said head.

2. A method as set forth in claim 1 comprising, positioning a secondpair of circumferentially adjustable work-engaging draw rings in contactwith the other wall surface of said cylinder and in contact with bothsides of said other roll, and varying the lengths of said second pair ofsaid circumferentially work-engaging draw rings to provide additionalflow control of the cylinder material to said bead.

, 3. A method of rolling a deep bead as set forth in claim =1 whereinthe grain of said cylinder material lies parallel to the longitudinalaxis of the cylinder, said first step comprises the positioning of saidrolls on opposite sides of said cylinder with the grain ofthe cylindermaterial lying normal to the longitudinal circular axis of the head toprevent cracking thereof.

4. A method of rolling a deep head in a shell of thin gauge metal withinternal and external forming rolls for a joggle joint. 'This joggleobviates the necessity of '15 gaging means incontact with the other saidshell walls,

E7 varying the radial pressure of at least one of said means to controlaxial flow of the material past both of said means, and rolling saidbead with both said means contiguous with the opposite sides of one ofsaid rolls.

5. A method as set forth in claim 4 wherein the bead stifiened shell isan endless stiffener comprising a plurality of arcuate strips placedend-to-end with their adjacent ends overlapped, and wherein the rollingstep comprises further rolling of the bead in said overlapped ends ofthe strips to form joggle joints in said bead stiffened stiffener.

6. In the stifiening of a shell of thin gauge metal by rolling a bead inthe peripheral surface thereof between an internally positioned formingroll and an externally positioned forming roll, the method ofcontrolling the axial flow of material for forming said head comprising,positioning circumferentially adjustable work-engaging hoop meansinternally of said shell in contact with the inner surface of the shellwall and contiguous with one side of one of said rolls, positioning asecond hoop means internally of said shell and in contact with the innersurface of the shell wall and contiguous with the other surface of saidone roll, and adjusting both of the hoop means to control the radialpressure and friction between both of said hoop means and said shell forcontrol of axial fiow of the bead forming material past both of saidhoop means.

7. An apparatus for deep draw roll forming of a head in a shell of thingauge material comprising: a pair of mating rolls for rolling the beadtherebetween, means in contact with one surface of the shell and incontact with a side of one of said rolls, second means in contact withsaid one surface of the shell and in contact with the other side of saidone roll, both of said means being adjustable for controlling the axialflow of the material of the cylinder to the mating rolls whereby therolls may form said deep bead.

8. An apparatus as recited in claim 7 including a set of two additionalmeans, one of said additional means being in contact with the othersurface of the shell and in contact with the side of the other roll, theother of said additional means being in contact with the other shellsurface and in contact with the other side of said other roll, both ofsaid additional means being adjustable for hearing against said othersurface of said cylinder for varying the radial pressure and frictionbetween both of said additional means and said cylinder for control ofsaid axial flow of deep bead forming material.

9. An apparatus as recited in claim 7 wherein said means comprisecircumferential adjustable work-engaging draw rings for acting againstsaid one surface of said cylinder for varying the radial pressure andfriction between said draw ring and said cylinder for control of saidaxial flow of deep bead forming material.

10. An apparatus as recited in claim 7 wherein each of said means isadjustable to an expanded position and to a contracted position, areleasable lock mechanism included in said means for locking same incontracted position for ease of locating said means in contact with aside of a roll and for locking same in extended position for fixing saidmeans immovable relative to the shell.

11. An apparatus as recited in claim 7 wherein one of said means is anannulus, said annulus being split to provide two movable ends, one endbeing collapsible over the other end to provide contractability of saidannulus, and each of said ends including rollers mounted thereon tofacilitate contractability of said annulus.

References Cited in the file of this patent UNITED STATES PATENTS680,442 Schrnitt Aug. 13, 1901 971,838 Fulton Oct. 4, 1910 975,519Fulton Nov. 15, 1910 J1,330,804 Haskell Feb. 17, 1920 1,451,998 NeubauerApr. 17, 1923 2,239,696 Bohm Apr. 29, 1941 2,468,488 Coyle Apr. 26, 19492,712,340 Sandberg July 5, 195,5

